Photographic screen and process of making the same.



A. LFHNER, PHOTOGRAPHIO SCREEN AND PROCESS OF MAKING THE SAME.

APPLICATION FILED IEB.15,1909.

1,112,540; Patent ed Oct. 6, 1914 ALFRED LEHNER, or xntsrnnnacn, GERMANY, Assmnon, BY. mEsnE assmmn'rs, 'r'o msrmauxonaxcomraux, or nocnssrsa, NEW max, A CORIOBATIQN, or.

NEW onxly;

I 3 Making the Same; and I do herebydeclare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it ap ertains to make and use the same.

- his invention relates tothe art of multicolor screens such as are used 'in -color photography. Where these color screens-orfilte'rs have been produced by parallel or crosshatching this has hitherto always been done by printing the lines on plane surfaces or sheets. These lines, according to the nature of the process, serve either to mask or to prevent the passage of the rcolo'r rays, where they occur, or they may be of the various colors desired and of such a nature as to permit the passage through the screen of onlythe-correspondingcolor rays Where they occur. In the latter case, as .is wellunderstood, the picture printed in the vari- 'ous colors must be colored with such intensity that sufiici'ent absorption of the complementary rays occurs. In view of the fineness and the thinness of the lineswhich are thus printed on the screenysheet and in view of the necessity of maintaining such lines transparent, it has been found impossible hitherto to attain the necessary colorintensity for these lines to produce effective "color' screens for multi-color photography.

Where the lines printed on the surface serve merely as a color resist to mask the sheet, where they occur, against the action of the color or dye with which the sheet is to be afterWnrd treated, the'difiiculty just mentioned does not arrive, butthere still remains the objection common to .all print- 'ing methods-in this. art,-hitherto known,

that it is diflicult to obtain'the printed lines of resisting material distributed evenly and sufficiently sharp. These lines are usually very uneven, presenting contracted and expanded portions so that on coloring the surface thus hatched with the resist, a serviceable color screen can not be obtained.

.It is the object of the present invention Y Specification of Letters was. Application fil'ed February 15, 1909. SerialNo.-478,036.-

l' 'nq'rbemrnic scnE'EN 4ND or mains rim to remove these objectionsland at thesfiiie a Patented Oct.

time to devise a process for thispurpose which is both simple andiinex'pensive and ,oanbe readily carried out.

In ,order to attain fthis.obiect my. invention consists in themethod'and' features now to be described and the claims.

is had to the accompanying drawing in which- Figure 1 represents a transverse section 5 at a further stage of the method and Fig.

then. pointed out. in J '60 .In order to aid the description reference I 3 a diagrammatic plan view of a screen sheet treated according to a modified method, involving my invention. 7 For producing two-color screens according to this invention I proceed in the follow- 4 ing manner: A thin sheet or foil of suitable moldable plastic material, such as celluloid or other photographic plastic substance ispressed into intimate contact with a metallic die having the requisite hatching formed in relief on its plane surface, heat'bein'g eniployed in connection with this pressing operation. Either the die or the plastic sheet or both may be heated for this parpose, as will be well-understood bytli'ose similar plastic substances. The metal relief die for this purpose may be prepared by any suitable-method, such for example as ruling the same. with an acid resist and etching the surface. .By this compression.

and concurrent-heating an intaglio copy of the relief hatching on the metal surface or plate. is produced in the celluloid sheet.

. This intaglio hatchin is indicated inFig. 1

of the drawing, whic represents a greatly enlarged transverse section of a portion of the celluloid sheet provided with the said -hatching. The recesses 6 correspond to the nown in the art skilled in the art of molding celluloidand of printing, such as by rolling over the same a printers inking roller. "Thereby only the elevations a receive the ink or varnish or other resist, as indicated at 0 Fig. 2. The back of the sheet having been sufficiently protected by a suitable resist indicated by a: in Fig. 2, the said sheet is now immersed in a color bath, such as a concentrated solution of a dye in alcohol for a short time, whereby the recesses or depressions I) receive the color, as at d Fig. 2, While the rest of the surface of the sheet repels the dye or bath.

By suitably regulating the time of immersion and the degree of the concentration of the bath, any desired intensity of color on the exposed portions of the sheet may be obtained and the color can be uniformly applied.

The sheet having been dried, the resist on the elevations a and on the back of the sheet is removed with a suitable solvent, such as oil of turpentine and the elevations are now suitably colored. This may be done in a simple manner by passing over the sheet a roller covered with fine cloth or other textile and impregnated with an alcoholic dye solution. The elevations a may by this method be colored differently from the depressions or recesses b and the two colors can be so selected as to produce a two color screen suitable for usein color photography in amanner well-understood.

In order to reduce the fluidity of the alcoholic color solution employed, a thickening agent soluble in alcohol, such as resin, may be added thereto. In this manner an accurate and effective two-color screen may be obtained without difiiculty.

j To produce three-color or four-color photographic screens I proceed as follows: I produce parallel hatching in relief .onthe plastic transparent sheet in the manner above described for two-color screens and I color the 'intaglio lines 6, in the manner described by covering the relief lines a and the back with a color resist or mask and 'then immersing in a color bath, for example in a solution of rhodamin. The resist is then removedand the surface of the celluloid or other plastic sheet provided with the parallel hatching is again pressed onto the metallic hatched die while being heated, the sheet "being so placed, however, that its hatchings form an -angle,preferably a right angle, with the hatchings on the metallic die. --Thereby the surface ofthe celluloid 'or 'otherplastic sheetis covered with a series of parallel hatchings' in relief-asin the first part of this method, but these hatchingsnow are at an angle,.preferably a right angle, to the ositi'on of the first series of hatchingsfi. --n0w cover the rdief portions or ridgesand the back of the' sheet with a resist and againimmerse' the same 'in a color for erample malachite green." On again remo'vmgthe resist a reticulated color screen is obtained in which one set of lines or bands have been applied in red while the other series of lines, crossing the first, is applied in green. If the breadth and the distance between the bands of the two series have been made equal to each other, a color design will appear on the surface of the screen sheet which is represented in Fig. 3, in which one-fourth of the quadrangular stipples are green, these stipples being represented at e and one-fourth, represented at f, red. The quadrangular stipples or patches 9 which occur atthe crossing points of thetwo-color bands will be nearly black if the colors have been properly chosen. A fourth portion of the surface consisting of portions h of the elevated lines or ridges will be without color. To these elevated white portions the required third color is then applied by coating the surface of the.

sheet with a layer of actinic material producing the desired color on exposure to light. Such a material is bichromatized gelatin or isinglass or bichromatized casein.

.Havin'g applied a coating of such materials rangles occupying one-fourth of the surface of the screen and which are due to the superposition of two colors do not interfere with the production of pictures having bright and glowing colors. This has been shown by practice. This is probably due to the extreme transparency of the celluloid which is employed in thin layers or films and to thecolors employed. Should it be desired, however, to avoid this production of black or. substantially complete light absorbing portions at the points of intersection of the color bands, this object may be attained by a judicious selection of the colors and the consequent production of a four color screen; For example if weselect a four color systememploying the colors red, orange, yellow and blue-green, one series of bands will be made yellow and the series of color bandscro'ssing the same willbe made red. In all other respects the method above described for the three-color system will be followed in this method. The colors of the quadrangular patches, at the intersection of the two series of color bands will now be sheet. According to this last method when gnome using celluloidasthe :screen film a is necessary to employ alcoholic color baths for the first twoapplications of color.

same with a thin layerof a color receiving substance, gelatin, casein or the like for aqueous coloring baths or pyroxylin for alcoholic color baths.

Since the .color lines or stipples in the color screens prepared as hereinbefore described are in difierent planes the screen sheet is finally compressed between plane surfaces heated coincidently, whereby the relief color portions are made flush or substantially fiush' with the depressed portions and a practically or wholly flat multicolor screen results. p

While in the processes described above the color in-the initial coloring steps is applied by immersing thescreen sheet in a. color bathjit is possible to apply such color with a brush previously dipped in a color solution, in which case it is not neces a yv to cover the back of the screen sheet with a resist. Although I consider the immersing step the preferable one. I amnot confinedto the same for purposes of this invention.

It will be noted from the above that a multicolor screen made under myinvention consists of a sheet of any suitable material,

. such as cellulose material or other plastic material which is faced with variously colored areas; On this screen one or more of the colors are arranged on relief portions of the sheet, integral with said sheet, and which are compressed to be substantially flush with said. sheet material.

What I claim and desire to secure by Letters Patent is 1. In the "art ,of' preparing 'multicolor screens for color, photography, the-process which consists in coating the relief portions of a relief hatched screen-sheet with a color resist, then applying color tothe intaglioportions of the sheet-and then'removing the 1 resist. j s

2. The process of preparing screen sheets having relief portions thereom for color photography, which consists in coating the relief portions of said sheetwith a color resist, then applying color to the surface thereof and then removing the resist.

3. The process of preparing multicolor from that in the color bath.

screens for color photography, which consists in coating the relief portions of a relief hatched screen sheet with a color resist', then applying color to thesurface of the screen sheet, removing the resist and color'ing the relief portions.

'4. The process of preparing multicolor screens for color photography, which consists in hatching a screen sheet in relief, coating the relief portions with a color resist, then applying color to the surface of the screen sheet, then removing the resist and coloring the relief portions.

-5. .The process of preparing multicolor screens for color photography which consists in coating the relief portions and the back of a-screen sheet with a color resist,

then immersing the screen sheet in a color.

bath, then removing the resist and coating the relief portions with a color different .6. The process of preparing multicolor screens for color photography, which consists in hatching a screen sheet, provided producing the desired color under the action of light, and then exposing the screen sheet to light passing through the back of said screen sheet.

7. The process of preparing multicolor screens for color photography, which consists incovering the relief portions of the surface of a screen sheet hatched in relief with a color resist and applying color to the surface, then removing the resist and forming relief hatching on the said surface with a color resist at. an angle tothe first system of hatching again covering the relief portion of "the surface with a color resist and applying another color to the surface, then removing the resist and coating the surface with an actinic substance capable of pro-" 'back ofa. relie hatched screen sheet with a color resist and immersing the screen sheet in a color bath, then removing the. resist and relief hatching the surface at an angle to I the first system of hatching, again covering the relief portions and back with a'color resist and immersing the screen sheet into an other color bath, then again removing the resist and coating the sheet with an actinic substance capable of evolving a third color 1 under the action of light and then exposing the screen sheet to light passing through the back of saidsheet.

, 9. A multicolor screen for color photography consisting of asheet faced with variously colored areas, the material of the sheet bounding. said areas presenting one of the .colors being integral with the sheet and compressed to be substantially flush with the surface thereof. p 5

10. A multicolor screen for color photography consisting of a sheet permitting the passageof light, said sheet being 'facedwith variously colored areas, the material of the sheet bounding said areas presenting one of-the colors being integral with the sheet music raphy consisting'of a sheet of photographic 20 plastic material faced with variously colored material of the sheet bounding areas, the said areas presenting one of the colors being integral with the sheet and compressed to be substantially flush with the 25 surface thereof. 4

In'testimony whereof I hereunto afiix my signature in the presence oftwo witnesses. DR. ALFRED LEHNER.

lVitnesses:

CARL GRUND, j n JEAN Gmmn. 

